Temperature Affects Astringency Removal and Recurrence in Persimmon

Abstract

Astringency was removed from 'Triumph' persimmons by immersion in water at 40°C for 5 hr or 6O"C, for 1 hr. Similar treatments at 20" and 8O"C, had no effect on astringency reduction. Subsequent application of 80% CO2 for 48 hr was effective for 20"C-treated fruit but not for 80YXreated fruit, which became nonastringent only after exposure to acetaldehyde. Extending the 60°C treatment beyond 2 hr resulted in recurrence of astringency, which was not reduced by subsequent COz treatment. Astringency also recurred in CO+eated nonastringent tit, when exposed to high temperatures. The disappearance and recurrence of astringency correlated with amount of methanolsoluble tannins.

Selected primary and secondary metabolites in fresh persimmon (Diospyros kaki Thunb.): A review of analytical methods and current knowledge of fruit composition and health benefits

“…On the other hand, as pinpointed for the origin of astringency perception in the oral cavity, tannins bind readily with proteins to form quite indigestible complexes and can therefore be considered as antinutritional compounds in herbivores (Salunkhe, Chavan, & Kadam, 1989). Moreover, as suggested by Ben-Arie and Sonego (1993), tannins resolubilised during human digestion can be involved in the occurrence of persimmon bezoars, hard masses occasionally found in the human stomach or intestine (Seung et al, 2007), with a higher frequency in patients subjected to gastric surgery (Moriel et al, 1983). In this regard, Ben-Arie and Sonego (1993) hypothesized that the formation of persimmon bezoars is caused by resolubilization of insoluble tannins by the high acidity occurring in the human stomach during digestion and successive re-coagulation of solubilised tannins with proteins and/or other macromolecules present in the stomach.…”

“…Moreover, as suggested by Ben-Arie and Sonego (1993), tannins resolubilised during human digestion can be involved in the occurrence of persimmon bezoars, hard masses occasionally found in the human stomach or intestine (Seung et al, 2007), with a higher frequency in patients subjected to gastric surgery (Moriel et al, 1983). In this regard, Ben-Arie and Sonego (1993) hypothesized that the formation of persimmon bezoars is caused by resolubilization of insoluble tannins by the high acidity occurring in the human stomach during digestion and successive re-coagulation of solubilised tannins with proteins and/or other macromolecules present in the stomach. The re-coagulating capacity of resolubilized tannins has been experimentally highlighted by Seung et al (2007) on a patient with an intestinal persimmon bezoar resulting from the solubilisation of a previously diagnosed gastric bezoar.…”

Determination of changes in some characteristics of persimmon during dehydration at different temperatures

“…Anaerobic conditions stimulate production of acetaldehyde and ethanol by the fruits; the mechanism involves soluble tannins in the fresh fruit becoming insoluble upon condensation or polymerization with acetaldehyde (Pesis et al, 1988;Taira & Ono, 1997). A method commonly used is to enclose the fruit for 1-2 days in a CO 2 -enriched atmosphere (>80% CO 2 ) (Ben-Arie & Sonego, 1993;Pesis et al, 1988). Pesis et al (1988) indicated, astringency was removed more rapidly under CO 2 than under vacuum and the de-astringency process under N 2 was the slowest.…”

“…Most research relating to persimmon has been on storage conditions (cold and controlled atmosphere storage) after harvest, and has been carried out to determine astringency, color and firmness (Ben-Arie & Sonego, 1993;Kitagawa & Glucina, 1984;Pesis, Levi, & BenArie, 1988). Furthermore in some studies, invertase and pectin esterase were isolated and their characteristics were investigated (Alonso, Howel, & Canet, 1997;Iwatsobu, Takahashi, Nakagawa, Ogura, & Sato, 1992).…”

“…The removal of astringency from persimmon fruits has been achieved by several methods, based on exposing the fruit to anaerobic conditions or to products of anaerobic respiration (Ben-Arie & Sonego, 1993). Anaerobic conditions stimulate production of acetaldehyde and ethanol by the fruits; the mechanism involves soluble tannins in the fresh fruit becoming insoluble upon condensation or polymerization with acetaldehyde (Pesis et al, 1988;Taira & Ono, 1997).…”